As the demand for fuels such as aviation fuel and chemicals such as propylene glycol increase worldwide, there is increasing interest in sources other than petroleum crude oil for producing the fuel or chemical. One source is renewable feedstocks including, but not limited to, plant oils such as corn, jatropha, camelina, rapeseed, canola, soybean and algal oils, animal fats such as tallow, fish oils, and various waste streams such as yellow and brown greases and oily streams recovered from sewage sludge. The common feature of these feedstocks is that they are composed of mono- di- and tri-glycerides, and free fatty acids (FAAs). Most of the glycerides in the renewable feed stocks will be triglycerides, but some may be monoglycerides or diglycerides. The monoglycerides and diglycerides can be processed along with the triglycerides.
There are reports disclosing the production of hydrocarbons from oils. For example, U.S. Pat. No. 4,300,009 discloses the use of crystalline aluminosilicate zeolites to convert plant oils (e.g., corn oil) to hydrocarbons (e.g., gasoline), and chemicals (e.g., para-xylene). U.S. Pat. No. 4,992,605 discloses the production of hydrocarbon products in the diesel boiling range by hydroprocessing vegetable oils such as canola or sunflower oil. Finally, US 2004/0230085 A1 discloses a process for treating a hydrocarbon component of biological origin by hydrodeoxygenation followed by isomerization.
However, existing processes for converting fats and oils to biodiesel and glycerol have been criticized because of the quality of the diesel produced and the oversupply of glycerol. In addition, current processes for producing transportation fuel from renewable feedstocks have been criticized because of concerns over the high investment cost and operating costs.